I'm on my way to put my water injection on duty, but unsure of what cc size nozzle must be used. Have 75cc, 90cc and two 300cc's.....boost pressure switch just arrived today.
My spec's as follow:
GT28RS
4FPR
3" straight DP to the tail.
Stock injectors, Walbro, SIP,FMIC, and Flea remap......
Any opinions will be considered.
Thanks.

Need some more information to advise....

What pressure is the water injection pump running at?
Does the water pressure increase with boost?
Do you have a graph, power against RPM?
What are inlet temperatures at the moment?
What is your target inlet temperature?

What programmable (or pressure switch) control over water flow do you have? i.e. single stage (one injector) or can you control a secondary injector?

1 - 150 psi
2 - No
3 - No
4 - Have no time to observe, but no complains......
5 - i'm not in pursuing big power, map is for 1.4 bar, and i just want to be safe, have unused w/m inj kit in my garage, why not to try it.....
6 - Only single injector

OK. Problem is you ideally you need more water at peak torque and less at peak power. As you only have control for one nozzle, use this formula:

(9 x max torque (lb/ft) x rpm (peak torque)) all divided by 100000

e.g. (9 x 300 x 5000)/100000 = 135cc/min

This will give you a ratio of about 12.5% water (or water/methanol) per unit of fuel (by weight)

Another way you could estimate nozzle flow rate is using the maximum flow in cc/min of of your fuel injectors, in which case:

Fuel injector flow rate x 5 x 0.8 x 0.73 x 0.125 = water nozzle flow rate.

Where:

5 = number of injectors
0.8 = 80% duty cycle
0.73 = density of petrol
0.125 = 12.5%

So, for 360cc fuel injectors you get:

360 x 5 x 0.8 x 0.73 x 0.125 = 131.4cc/min.

I can bet half of my car, that nobody could explain this better.....
Many thanks.....

Front end or rear end?

Sorry - can not understand your question......
PS - i will use windscreen wash tank for water/meth, and just put another tank from Alfa 156 on the other side to feed the wipes with water......

He asked which half of the car give for a better explanation

Oh, sorry.....
Rear end off course, and most of all the part where the fuel cap sits......

OK, last questions and chance for some to win half of my car....
Today i removed outer part of the intake in order to drill a hole for the nozzle. As you can see from the picture i need to know best location for it.
Before of after AIT sensor? It sits straight below number 17, so maybe hole and nozzle at 17 is'nt good idea.

Because intake will be off the car for few days, and i think it may be good idea to rasp intake ports, i plan in mid summer to strip and overhaul the entire engine, porting head and intakes(infact i have spare head from 20V/NA ported and ready to put in), and hope to do that part now, and save some time afterwards.
How much i can take off from it - 1-2-3 mm????


Thanks again......

I think in the area of 10-11-12 would be best. That way you are spraying in the same direction as the airflow, and the engine will see the correct charge temperature.

Yes, also thought same location will suit fine........